Anyone working on an RPG, particularly a portable RPG, needs to take a long, hard look at The World Ends with You, Square's recent DS game. It's filled with interesting ideas, like the slider that lets players trade levels and difficulty for item drops, or the ridiculously complicated cross-screen combat.
Most of these features are interesting, or amusing, or helpful, but they're not revolutionary. No-one's going to imitate the multitasking combat, and its "pin" system is really just a weirdly limited version of the Mega Man Battle Network games. The setting has been lauded by reviewers, but that's only because nerds love to obsess over Tokyo's Shibuya district, and the storyline is the same old adolescent angst that Square's been peddling for years now.
But if designers want to learn from TWEWY, they need to steal its experience system. Because instead of the usual grind, you can also level up in the game by turning it off and doing something else for a while. The next time you turn it on, for up to a week, your character gains experience for the the time elapsed--not enough to incentivize not playing, but it certainly takes the sting out of setting it aside if I get frustrated.
It's an astonishing development, in a way, because it reveals what almost everyone knows but game designers seem reluctant to admit: nobody likes the level grind. No-one wants to sit around playing against the same enemies over and over again in order to proceed--nobody sane, at least. That the entire MMO industry has been built around this process is a tribute to its social appeal and the polish of the surrounding parts, not the value of the grind.
I don't expect all games to implement progress-via-absence in this exact form, but at the very least it would be nice if software were smarter about time. I can't count the number of games that I've wandered away from, tried to return to at a later date, and given up simply due to lack of incentive and loss of familiarity. It would seem like an obvious choice for games (or any interactive software, honestly) to check if I've been away and adjust accordingly, perhaps asking if I need a refresher on the mechanics or a temporary difficulty drop while I get reacquainted with it. Considering that the statistics say most games go unfinished, why not make the return process as painless as possible?